Automatic guy wire tensioning device

ABSTRACT

AN AUTOMATIC PAYOUT AND RETRACTION DEVICE FOR A SET OF GUY WIRES USED IN ERECTING A VERTICAL MAST CONSISTS OF A CONTROLLER WHICH SUPPLIES ELECTRICAL POWER TO TWO TENSIONER UNITS WHICH CONTROL THE GUY WIRES.

United States Patent Inventors Walter L. Blmk Upper Fills; Frank 1... Holiord, Towson, Md.

Appl. No. 823,055

Filed May 8, 1969 Patented June 28, 1971 Assignee The United States of America as represented by the Secretary of the Army AUTOMATIC GUY WIRE TENSIONING DEVICE I Claim, 2 Drawing Figs.

254/184, 254/150, 52/121 Int. Cl. 866d 1/48 Field Search 254/184,

PULLEY [56] References Cited UNlTED STATES PATENTS 1,323,299 12/1919 MacFarlane 254/184 2,005,891 6/1935 Elberty, Jr. 74/675 2,389,047 11/1945 Heinz 74/675 3,033,529 5/1962 Pierrat 254/150 3,195,831 7/1965 Shriner et a1. 254/184 462,993 11/1891 Pfetch 254/150 FOREIGN PATENTS 350,596 6/1931 Great Britaih 52/121 Primary Examiner-Even C. Blunk Assistant Examiner-Merle F. Maffei Attorneys-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and James T. Busch ABSTRACT: An automatic payout and retraction device for a set of guy wires used in erecting a vertical mast consists of a controller which supplies electrical power to two tensioner units which control the guy wires,

AUTOMATIC GUY WIRE TENSIONING DEVICE BACKGROUND OF INVENTION The present invention relates generally to an electromechanical control device and in particular to such a device used to control a vertically erected mast.

In the past a vertically erected mast had to be supported completely at its base during erection because no practical method existed for controlling the payout and retraction of guy lines. The capacity of a vertically erected mast is described in terms of the weight and size of the vertical payload it will support at particular values of wind loading. The necessity for erecting the mast in a configuration supported only at its base seriously limited this capacity.

SUMMARY OF INVENTION The general purpose of the invention is to provide a means for the automatic payout and retraction of a set of guy wires during erection of a vertical mast which can be added to existing mast equipment. Some of the advantages of the invention are that it can be added to most types of vertically erected mast equipment with only minor modifications to add mounting holes; it is automatic and it is highly effective in controlling the tension in a set of guy wires during erection and retraction of vertically erected masts. In addition no additional personnel are required to erect the mast and the equipment increases the payload of any vertically erected mast several fold.

DESCRIPTION OF DRAWING The exact nature of this invention will be readily apparent from consideration of the following specification relating to the annexed drawings in which:

FIG. 1 shows a conceptual drawing of the control device used to control a vertical mast; and

FIG. 2 shows a schematic diagram of a tensioner unit.

DESCRIPTION OF PREFERRED EMBODIMENT Referring now to the drawing wherein like reference characters designate like or corresponding parts in the separate views.

There is shown a tensioner unit 10, two or more of which are the basic units of the system. This unit is composed of the five principal component assemblies shown in FIG. 2. The unit functions in the following manner. The torque motor 11 is essentially a constant torque device that will produce approximately a fixed torque at its output shaft whether stalled, running in a positive direction as an ordinary motor, or being driven backwards by externally applied forces. The torque produced by the motor is amplified by the gear reduction 12 and applied to tape drums 13, which are attached to the two side gears of the differential 14. The gear reduction is a threestage unit with an overall ratio of 203/ l. The characteristics of the differential are such that, with the spider locked, one drum cannot rotate without a corresponding movement of the other. Furthermore, the torques applied at each drum are added by the differential and at all times will sum to a value approximately equal to the torque being delivered to the differential by the torque motor. When the mast 15 is being extended and the tapes are pulled out, torques are generated at the drums that sum to a value slightly above that produced by the torque motor and the torque motor is driven backwards. When the mast is being lowered, the reverse situation exists and the torque motor rotates in a positive direction as a normal motor is expected to do and reels in" the tape. Since the differential sums the torques applied to the tape drums, automatic adjustment is provided to resist the action of shifting wind loads. For instance, suppose the wind loads are zero; then the torque produced by the torque motor divides evenly between the tape drums and equal tensions will result in the two cables. Now, suppose a wind load occurs; the tension in the windward cable will increase while that in the leeward will decrease with the difference being exactly equal to the amount of windload.

During this shifting of the cable tensions, the sum of the cable tensions does not change, only its distribution from one cable to the other takes place: The torque motor is undisturbed by this shifting of the cable tensions and continues to deliver. a constant torque to the differential which is distributed in the manner just described.

The spider of the differential is held stationary by the action of an irreversible worm drive 17. That is, the worm wheel will respond only to the driving action of the worm. The reduction ratio of the wonn drive is 30/ l. The only way that the payout of one cable can be adjusted relative to the other is by action of the worm drive. Rotation of the worm in a particular direction will cause one cable to pay out while the other retracts. If the rotation of the wormis reversed, the effect on the cables is also reversed. In this manner the spatial position of the control point at the mast can be shifted, thereby accomplishing any desired change in the vertical condition of the mast.

The brake shown on the end of the motor is a fail-safe" device arranged so that rotation of the torque motor shaft is restrained when electrical power is off. This is accomplished by the action of a mechanical spring energizing a friction clutch. When electrical power is applied to the motor, it is applied simultaneously to a coil winding in the brake which causes an armature to move and overpower the force of the spring. This removes the plate pressures in the friction clutch and the clutch frees the restraining force on the motor shaft. If electrical power to the torque motor is interrupted for any reason, intentionally or otherwise, the brake immediately en gages, thereby conditioning the tensioner unit to resist any further movement of the control cables.

The output to the control cables 18 is accomplished through a pair of steel tapes 21 which are stored on drums which in turn are attached to the side gears of the differential. The method of converting the torques of the torque motor to cable tensions is quite critical to the overall design of the tensioner unit. The tape length on each drum is 36 feet which is established by the geometry of the guying system. The tape is 0.010 thick and 0.500 inches wide. As the mast increases in height the cable tensions required to stabilize the mast against the wind loads also increase, but as the tapes pay out, the cable tensions automatically increase due to the radius of the tapes on the drums becoming smaller.

A controller 19 is provided which serves as a junction point from which electrical power is metered to the two tensioner units. A pair of switches consisting of a mast selector switch and an up-down switch are used to select the operational mode. The selector switch is positioned to correspond to the mast configuration being used and the up-down switch is set at the appropriate position depending upon whether the mast is going up or coming down.

It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that modification may be made therein without departing from the scope of the invention as set forth in the appended claims.

We claim:

1. In a mast stabilizing system wherein several pairs of guy wires vertically support a mast with one end of the guy wires attached to some vertically extended portion of the mast and the other ends of said guy wires are fed through a pulley system for easy adjustment of the guys and attached to an automatic guy wire tensioning device mounted in near proximity to the base of the mast, an automatic payout and retraction device for maintaining a constant tension on each set of guy wires disposed on opposite sides of the vertically supported mast, comprising:

a pair of drums having tape wound thereon for controlling the tension on a pair of guy wires to which said tapes are connected;

a differential unit interconnecting the pair of drums;

a gear reduction means;

said differential unit axially connected to the gear reduction means through one of said pair of drums;

counter support cable and thus greater tension on one drum than another, the increased tension in the one drum is exactly offset by an equal decrease in tension in the other drum such that the sum of the tension on both drums is added within the difierential and at all times will sum to a value approximately equalto the torquebeing delivered to the differential by the torque motor. 

